docs: def is_compression_coordinate(ds, variable):
      '''
      Returns True if the variable is a coordinate variable that defines a
      compression scheme.
  
      :param netCDF4.Dataset nc: An open netCDF dataset
      :param str variable: Variable name
      '''
      # Must be a coordinate variable
      if not is_coordinate_variable(ds, variable):
          return False
      # must have a string attribute compress
      compress = getattr(ds.variables[variable], 'compress', None)
      if not isinstance(compress, basestring):
          return False
      if not compress:
          return False
      # This should never happen or be allowed
      if variable in compress:
          return False
      # Must point to dimensions
      for dim in compress.split():
          if dim not in ds.dimensions:
              return False
      return True